Not my recommended diagnostic approach

No, not a post about obscure Reba McEntire and Kevin Bacon projects of the 1990s, but the rhythmic shaking movements  that may be seen in your patients.  Step one with any diagnostic dilemma, history and physical. First, describe the tremor.

• Rest tremor: Occurs at rest, with affected body part fully supported, goes away with action. It gets worse with movement of another body part (repetitive moving of the unaffected arm) or with mental stress (ask patient to count backward).  You should think about Parkinson’s Disease in patients with rest tremor, although PD can present with action tremor as well.
• Action tremors: Most tremors are in this category, which is subdivided further into postural, kinetic, or intention. The most commonly diagnosed action tremor is Essential Tremor, it can present with any of these subtypes.
  • Postural tremors get worse when maintaining a position against gravity.
  • Action tremors are worse when doing an activity, walking, writing, holding a cup, etc.
  • Intention tremors are action tremors that get worse at the end of the activity. This is the tremor that is worse as the patient gets closer to the target on a Finger-Nose-Finger test. Think about a cerebellar issue in a patient with this type of tremor.

Now that you have described the tremor, it is useful to think of the features of different tremor types to help you sort out the diagnosis.

Parkinsonism:  Classically a pill rolling, resting tremor of the hand, that starts unilaterally.  As with other rest tremors, it gets worse with movement of another body part.  This may mean that it seems to be exaggerated with movement, like walking, but if you look closely you notice that the tremor stops and starts again when the patient assumes a new rest position.  Look for other symptoms of PD: bradykinesia, postural instability, rigidity, shuffling gait, masked face.

Physiologic tremor.  Everyone experiences this, but it is generally complained about unless it becomes exaggerated with caffeine, medicines, fatigue, or stress. Physiologic tremor is low amplitude, high frequency tremor present at rest or with action, and comes and goes with exposure to above stressors. Commonly prescribed medicines that can exaggerate tremor include stimulants, steroids, tricyclic antidepressants, atorvastatin, and verapamil.

Essential Tremor: The most common pathologic tremor, it is classically a symmetric, postural action tremor of the hands and wrist, but it may involve head, voice, or lower extremities.  It is generally severe enough to impact daily life, and patients may quit working due to the tremor.  About 50% of patients will describe a family history, and then it may be called familial tremor.  There should be no other neurologic signs.  It may get better with alcohol, and doesn’t get worse with caffeine.

Cerebellar Tremor: Is a slow action tremor, usually an intention tremor, and is generally found with other neurologic signs like ataxia, dysmetria, and hypotonia.  Differential diagnosis includes multiple sclerosis, stroke, and brainstem disorders.

Psychogenic Tremor: And of course, there is a psychogenic tremor. It may have abrupt onset, spontaneous remission, and changing characteristics.  It tends to occur in patients with psychiatric disorders and other somatizations.

Check out this article for a great summary: Crawford P, Zimmerman E. Differentiation and Diagnosis of Tremor. Am Fam Physician. 2011;83(6)697-702.